This invention relates to an eccentric tool rest capable of moving a rotary tool in an axial direction in a lathe or the like which has the milling function.
In a lathe having the milling function, it is frequently required that machining, such as key groove machining, is performed by a rotary tool.
Heretofore, in response to such requirement, there was proposed a structure wherein a rotary tool is rotatably disposed within a casing, the tool being eccentric with respect to the center of the casing, the rotary power being transmitted to the rotary tool from the center of the casing through a gear train.
However, in such structure as mentioned above, it was required to dispose within the casing a spindle of the rotary tool, and a gear train and a driving shaft for transmitting driving power to it. Therefore, the diameter of a spindle of the rotary tool is obliged to be very small with respect to the diameter of the casing since the spindle is interposed between the driving shaft placed at the rotary center of the casing and the inner wall of the casing. In order to make the diameter of the tool spindle large for performing a heavy cutting by means of a large torque, the diameter of the casing is required to be made large. Such a large casing is inconvenient as a structure which is placed on a turret. In addition, the large casing restricts the arrangement of other tools, and therefore disturbs any attempt to improve the performance of such a turret.
The present invention seeks to overcome the above-mentioned shortcomings. It is therefore a general object of the present invention to provide an eccentric tool rest in which the diameter of a spindle of a rotary tool can be made relatively large within a casing with respect to the diameter of the casing.